1. Field of the Invention
The present invention relates generally to a printing apparatus. More specifically, the invention relates to an ink-jet printing apparatus for textile printing performed by ejecting ink toward a cloth.
2. Description of Prior Art
In a printing apparatus employing an ink as printing agent, an ink is generally supplied at the timing where the ink provided at a predetermined amount in the printing apparatus is used out or the remaining amount of the ink becomes small. Supplying of ink is performed by exchanging an ink cartridge storing ink to new one or by supplying the ink to an ink tank to refile it.
In the printing apparatus, such ink supply operation is enabled by stopping printing operation in response to an ink supply command automatically generated by detecting spending out of the ink or manually entered by the operator, for example. However, in typical printing apparatus, even when such ink supply command is detected, on-going printing operation at the detection is continued and printing operation is terminated after completion of printing operation, for the current page, for example, for enabling ink supply. Namely, since the conventional printing apparatus has a margin of remaining amount of ink upon detection of spending out, the foregoing process should not cause any significant problem.
However, when an elongated rolled paper or cloth (a continuous printing medium) is used as printing medium, the amount of image to be continuously printed is relatively large. In such case, even after detection of the ink supply demand, state it is likely to require printing for large amount of image, and the printing operation of non-ink state likely exists and continues for a long time. In such case, it is possible to cause failure in a printing head or so forth. Particularly, in case of so-called bubble-jet printing apparatus employing an ink-jet head assembly, in which the ink-jet head generates bubble in the ink utilizing heat energy and the ink is ejected by generation of the bubble, continuing of printing under the condition where the ink is spent out, may results in damaging of the head.
As a solution for this, it may be considered to terminate printing operation at the timing of spending out of the ink for supplying ink. However, this should make on-going printing incomplete to waste printing medium and ink. Also, in case of large amount printing, the printing period spent becomes wasted to cause degradation of efficiency.
As another solution, for example, an ink reservoir is provided at a location out of motion range of the printing head and so forth in printing operation, and is connected to the printing head by means of movable tube or so forth. With such arrangement, when shorting of ink is detected by a ink remaining amount sensor, the operator may supply new ink to the ink reservoir so that printing operation can be continued without interruption and without causing possibility of damaging of the head.
However, even in this case, upon shorting of ink, for instance, at the occurrence of alarm signal of the ink remaining amount sensor upon detection of shorting of ink, ink supply operation per se is inherent. Also, since the printing operation will never stop, when continuous printing is to be performed for long period, the operator should monitor shorting of the ink throughout the printing period so that the ink can be instantly supplied at the occurrence of shorting of the ink.